The present invention relates to an ink liquid supply system for an ink jet system printer of the charge amplitude controlling type wherein a printer head is driven to reciprocate across the printing region.
In the conventional ink jet system printer of the charge amplitude controlling type, a constant pressure ink liquid supply pump is employed, wherein the mass of the ink droplets and the velocity of the ink droplets emitted from a nozzle are variable depending on the ink characteristics such as the viscosity. These variations will provide a distortion on the printed character. Recently it has been proposed to employ a constant flow rate ink liquid supply pump in order to compensate for the ambience temperature variation. A typical constant flow rate pump and operation modes thereof are described in copending application Ser. No. 70,639 (DOS 2,934,947), now U.S. Pat. No. 4,278,984 issued July 14, 1981, entitled, "CONSTANT FLOW RATE LIQUID SUPPLY PUMP", filed on Aug. 28, 1979 by Masafumi Matsumoto and Matahira Kotani and assigned to the same assignee as the present application, or Ser. No. 97,389 (DOS No. 2,948,131), now U.S. Pat. No. 4,263,602 issued Apr. 21, 1981, entitled "CONSTANT FLOW RATE LIQUID SUPPLY PUMP", filed on Nov. 26, 1979 by Masafumi Matsumoto and Matahira Kotani and assigned to the same assignee as the present application.
However, the above-mentioned constant flow rate ink liquid supply pump cannot ensure stable ink droplet formation when the ambience temperature is rapidly changed. Moreover, the stable ink droplet formation is not expected when the last printing operation is terminated at, for example, 40.degree. C. and the present printing operation is initiated at, for example, 5.degree. C. This is mainly caused by a pressure accumulator which is required for removing the pressure pulsation. When the pressure accumulator has a small capacity, the pressure pulsation cannot be removed. When the pressure accumulator has a large capacity, the system cannot respond to the rapid temperature variation.
Accordingly, an object of the present invention is to provide a novel ink liquid supply system in an ink jet system printer of the charge amplitude controlling type which has a reciprocating printer head.
Another object of the present invention is to provide an ink liquid supply system including a constant flow rate liquid supply pump and a small capacity pressure accumulator.
Still another object of the present invention is to provide a control system for correlating the pump drive with the printer head movement in an ink jet system printer of the charge amplitude controlling type.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, an ink liquid supply system includes a constant flow rate ink liquid supply pump and a pressure accumulator of a small capacity for removing the pressure pulsation created by the constant flow rate ink liquid supply pump. The drive timing of the constant flow rate ink liquid supply pump is synchronized with the drive timing of a printer head which is driven to reciprocate across the printing region. More specifically, the initiation of the driving of the constant flow rate ink liquid supply pump is effected when the printer head is located at a position not effective for the actual printing, for examples, the left-most home position of the printer head.